Very often a product contained within a container does not fill the entire container's space with the remaining space (to be referred to herein as the “residual space”) containing a gas. Often, the gas's composition plays a role in the product's shelf life. This is the case, for example, in containers holding food products. Air, which contains about 21% oxygen, facilitates growth and development of microorganisms that degrade the food product. There are many apparatuses and method which have been proposed and developed aimed at replacing the air in the residual space with another gas having a desired composition. For example, in the case of food products such a replacement gas is typically nitrogen or carbon dioxide.
In the context of this writing the gas which is introduced into the container to fill the residual space will be referred to herein as the “replacement gas”. As will no doubt be appreciated, the nature of the replacement gas depends on the type of product and the type of desired effect. In the case of food products, a replacement gas will be a gas which has a composition such that it does not permit growth and development of microorganisms, particularly a gas essentially devoid of oxygen. In the case of other kinds of products the replacement gas may have a variety of different gas composition, for example: consisting of a chemically inert, e.g. a noble gas; consisting of a gas with a certain surface activity to treat or prepare the product; may be a disinfecting gas intending to destroy microorganisms which may be contained in or on the product; etc.